Most efficient way to remove unwanted vertices in an object with 59,000 points?
In edit mode, press C, that will enter you into a Circle select. Just hold LMB  and drag over what you want deleted. When you have selected all you want to delete, Right click. Then press delete (or x) and chose vertices.

There is also a border selection method, which works in ether edit mode or object mode. Press B, just drag with the LMB  held down, when you release it the selection is done.  Delete the same way as above.  If you selected too much you can unselect it by, dragging with the MMB  in either border select or circle select mode.